Virtual machine technologies are being widely applied to the field of information technologies and are penetrating into the field of communications. A hot migration technology is a great technical highlight for a virtual machine, and enables a virtual machine to migrate between two physical machines, and the migration process has little impact on service processing. An existing virtual machine hot migration technology uses a pre-copy method. In this method, all memory pages of a virtual machine are first copied from a source physical machine to a target physical machine, and all the memory pages are monitored in the copying process, where pages modified in the copying process are labeled as dirty pages; after copying of all the memory pages is completed, the generated dirty pages are copied. It should be noted that in the dirty page copying process, some memory pages may be also modified, and in this case, these modified memory pages also need to be labeled as dirty pages, so that these dirty pages can be copied from the source physical machine to the target physical machine next time dirty page copying is performed. In this way, dirty pages are cyclically copied to the target machine until a proportion of dirty pages is less than a preset value (for example, 5%), and after the proportion of the dirty pages is less than the preset value, migration of the virtual machine is performed, that is, the virtual machine is stopped, dirty pages which are not yet copied are copied from the source physical machine to the target physical machine at a time, and then the virtual machine is restored on the target physical machine.
However, in the cyclical copying process of dirty pages, as long as one byte of a memory page is modified, the memory page is labeled as a dirty page. Therefore, a great amount of changed temporary data in a system is cyclically copied to the target physical machine, thereby causing great time consumption of virtual machine hot migration and a great waste of resources such as CPU processing resources and network bandwidth of the system, and it is estimated that the percentage of wasted resources exceeds 90%. Therefore, how to reduce a quantity of times of dirty page cyclical copying caused by changes in a great amount of temporary data in a system and a quantity of dirty pages which are copied in each cyclical copying process, so as to reduce a system resource waste caused by virtual machine hot migration, is a problem urgently to be solved in the virtual machine hot migration technology.